Automatic guided vehicle

Abstract

In embodiments, an automatic guided vehicle includes a vehicle, a lift unit, a bumper, an extension detector, and a bumper controller. The vehicle is movable in at least a first direction. The lift unit is provided in the vehicle and lifts an object from below the object. The bumper is provided in the vehicle and is extendable and contractible in the first direction. The extension detector detects that the bumper has extended outward from the object in the first direction. The bumper controller controls a state of the bumper according to a conveyance state of the object by the vehicle.

What is claimed is: 
     
       1. An automatic guided vehicle comprising:
 a vehicle which is movable in at least a first direction; 
 a lift unit provided in the vehicle and configured to lift an object from below the object; 
 a bumper provided in the vehicle and configured to be extendable and contractible in the first direction; 
 an extension detector mounted on the bumper and detecting that the bumper has extended outward from the object in the first direction when it is detected that the object is not present above; and 
 a bumper controller which controls a state of the bumper according to a conveyance state of the object when transporting the object by the vehicle. 
 
     
     
       2. The automatic guided vehicle according to  claim 1 , wherein the bumper controller includes an extension setting unit which sets an extension of the bumper from the object according to a weight or a conveyance speed of the object. 
     
     
       3. The automatic guided vehicle according to  claim 1 , wherein the bumper controller includes a servo stiffness setting unit which sets a magnitude of a servo stiffness in positioning control of the bumper according to a weight or a conveyance speed of the object. 
     
     
       4. The automatic guided vehicle according to  claim 1 , further comprising:
 a movement controller which controls movement of the vehicle, wherein 
 the bumper controller includes a contact detector which detects contact between the bumper and an object, and 
 the contact detector outputs a movement stop command for the vehicle to the movement controller when contact between the bumper and an object is detected. 
 
     
     
       5. The automatic guided vehicle according to  claim 4 , wherein the contact detector detects contact between the bumper and an object when a rate of change of a positional error between a target position and a current position of the bumper in the first direction exceeds a first predetermined value. 
     
     
       6. The automatic guided vehicle according to  claim 4 , further comprising:
 an actuator which extends and contracts the bumper in the first direction, wherein 
 the contact detector detects contact between the bumper and an object when a rate of change of a current value of the actuator exceeds a second predetermined value. 
 
     
     
       7. The automatic guided vehicle according to  claim 1 , comprising:
 an actuator which extends and contracts the bumper in the first direction, wherein 
 the actuator is connected to the bumper via a timing belt. 
 
     
     
       8. The automatic guided vehicle according to  claim 1 , further comprising:
 an object detection sensor mounted on the bumper and configured to detect an object present therearound. 
 
     
     
       9. The automatic guided vehicle according to  claim 1 , wherein
 the bumper includes: 
 a first bumper disposed on one side of the vehicle in the first direction; and 
 a second bumper disposed on the other side of the vehicle in the first direction. 
 
     
     
       10. The automatic guided vehicle according to  claim 1 , wherein the vehicle is movable also in a second direction intersecting the first direction in addition to the first direction. 
     
     
       11. An automatic guided vehicle comprising:
 a vehicle which is movable in at least a first direction; 
 a lift unit provided in the vehicle and configured to lift an object from below the object; 
 a bumper provided in the vehicle and configured to be extendable and contractible in the first direction; 
 an extension detector which detects that the bumper has extended outward from the object in the first direction; and 
 a bumper controller which controls a state of the bumper according to a conveyance state of the object when transporting the object by the vehicle, wherein 
 the bumper controller includes a servo stiffness setting unit which sets a magnitude of a servo stiffness in positioning control of the bumper according to a weight or a conveyance speed of the object. 
 
     
     
       12. The automatic guided vehicle according to  claim 11 , wherein the bumper controller includes an extension setting unit which sets an extension of the bumper from the object according to a weight or a conveyance speed of the object. 
     
     
       13. The automatic guided vehicle according to  claim 11 , further comprising:
 a movement controller which controls movement of the vehicle, wherein 
 the bumper controller includes a contact detector which detects contact between the bumper and an object, and 
 the contact detector outputs a movement stop command for the vehicle to the movement controller when contact between the bumper and an object is detected. 
 
     
     
       14. The automatic guided vehicle according to  claim 13 , wherein the contact detector detects contact between the bumper and an object when a rate of change of a positional error between a target position and a current position of the bumper in the first direction exceeds a first predetermined value. 
     
     
       15. The automatic guided vehicle according to  claim 13 , further comprising:
 an actuator which extends and contracts the bumper in the first direction, wherein 
 the contact detector detects contact between the bumper and an object when a rate of change of a current value of the actuator exceeds a second predetermined value. 
 
     
     
       16. The automatic guided vehicle according to  claim 11 , comprising:
 an actuator which extends and contracts the bumper in the first direction, wherein 
 the actuator is connected to the bumper via a timing belt. 
 
     
     
       17. The automatic guided vehicle according to  claim 11 , further comprising:
 an object detection sensor mounted on the bumper and configured to detect an object present therearound. 
 
     
     
       18. The automatic guided vehicle according to  claim 11 , wherein
 the bumper includes: 
 a first bumper disposed on one side of the vehicle in the first direction; and 
 a second bumper disposed on the other side of the vehicle in the first direction. 
 
     
     
       19. The automatic guided vehicle according to  claim 11 , wherein the vehicle is movable also in a second direction intersecting the first direction in addition to the first direction.